Rate of resazurin ecperiment

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The resazurin experiment – Investigating the effect of concentration on rate an enzyme – controlled reaction in yeast

Preliminary experiment and prediction

The experiment we did was to see the colour change in resazurin when it was placed in a warmed water bath in different concentrations of yeast suspensions. We did this to see the rate of reaction in the yeast when it was heated to see how long it would take for the resazurin to change from blue to clear. There were different suspensions of yeast tried out each time.

I predict that the higher the concentration of yeast, the less time it would take to change the colour of resazurin because there would be more of the enzyme dehydrogenase for the resazurin to react with and therefore the colour would change quicker. Dehydrogenase is a catalyst that aids the process of reduction by speeding up the oxidation of the yeast. The reason the resazurin seems to disappear when the reaction is finished is because it changes colour when hydrogen is released through the yeasts process of anaerobic respiration. Glucose is gradually broken down in this process and energy is released. Hydrogen is also released in a process called oxidation, and when hydrogen is released the resazurin gains this hydrogen. The gaining of hydrogen is called “reduction” and molecules which gain this hydrogen are said to be reduced. I think that this will happen faster in my experiment when there is less distilled water in each yeast suspension.

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We did two experiments. One to measure the optimum temperature to use the water bath for the yeast to react, and one to determine the best amount of resazurin dye to use.

Experiment one – Finding the optimum temperature of water bath:

Changed: temperature of water in water bath (25, 49 and 72 degrees C)

Kept Constant: volume of yeast (10ml)

Volume of resazurin (2ml)

Results:

25 degrees C: n/a (took longer than 30 min)

49 degrees C: 123 secs

72 degrees C: 30 mins

I found that the best temperature to put the ...

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